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Balance in extension Balance in extension After placement of sliding spacer block, the medial joint space should open up 1 or 2 mm when valgus stress is applied with the knee in full extension. It is very important to avoid overstuff & overcorrection

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Balance in flexion, 2 to 3 mm laxity is suggested.in medial UKA after placing block For the balance in flexion, the thigh should be lifted with one arm to balance the flexion gap

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Marking of femoral rotation line Marking of femoral rotation line Next step for the Marking of femoral rotation line the center of the tibial spacer block is marked with a Bovie on the femoral condyle in different positions It should not be judged while the patella is everted or perpendicular line to the cut tibia bone can be chosen

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Distal femoral cut the distal femoral cutting guide is slided in extension and fixed with two pin and resected. The knee should be flexed 5 if the resected posterior slope of tibia is 5 to avoid hyperextension. shim can be used to manage the bone defect. Distal cut 가 flex 해지면 flex gap 이 tight 해진다

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Finishing cut ;Size If the size is proper, 1 to 2 mm of exposed bone. At the anterior edge

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Mediolateral dimension For the correct mediolateral position, The guide should be placed in the center of the femoral condyle,mediolaterally

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Rotation femoral rotation may follow the previously Marked rotation line or This guide should also be rotationally set so that the posterior cutting surface of femoral condyle is parallel to the resected tibia

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Fixation of finishing guide Posterior & Champer cut Finishing guide is fixed with two screw. at the Anterior margin of guide, bone is gouged slightly to accept the curved prosthesis While the MCL is protected with MCL retractor placed at femoral side, the posterior femur is resected and after anterior and posterior chamfer cut, two femoral peg hole is drilled

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The ideal correction as measured on the postoperative full weightbearing view will probably consist of a tibiofemoral axis crossing the knee between the tibial spines and the medial third of the tibial plateau for a medial UKA alignment Kennedy WR, White RP. Unicompartmental arthroplasty of the knee; post-operative alignment and its influence on overall results. Clin Orthop Relat Res. 1987;221:278-285 Argenson, Jean-Noel A MD; Parratte, corr 464 Nov 2007 P32